A clutch of this kind is described for example in the documents FR-A-No. 2 554 893, FR-A-No. 1 576 586 and DE-A-No. 36 00 972.
As is well known, a clutch generally comprises a reaction plate, and a clutch mechanism fixed to the reaction plate to clamp at least one friction disc therebetween. The mechanism comprises, overall, a cover and at least one pressure plate connected in rotation to the cover through the intermediary of tongues.
As described in the document FR-A-No. 2 554 893, the reaction plate may form part of a double damped flywheel and may be movable relative to an inertia plate, against the action of elastic means bearing on a flange fixed to the inertia plate.
In all cases the cover, the tongues or the flange form part for transmitting torque fixed respectively to the reaction plate, to the cover and to the pressure plate, or to the inertia plate, by fixing elements.
In these documents, the fixing elements consist of screws, or rivets provided with a head. In the arrangement with screws, the length of the blind hole does not need to be exact and the manufacturing tolerances of the part for transmitting the torque do not need to be precise. The disadvantage of this arrangement is the necessity to tap the blind hole, and the risk of the screws loosening, particularly as a result of vibrations.
In the arrangement with rivets having a shouldered head, the length of the blind hole must be exact as must that of the rivet. Moreover, it is also necessary to take into account the manufacturing tolerances of the part for transmitting the torque, and the clamping of this is influenced by the elastic rebound of the head of the rivet when the tool is withdrawn. In addition, when the mechanical forces involved are large, it is necessary to make grooves in the blind hole.
The object of the present invention is to overcome these disadvantages whilst enabling transmission of a large torque in a lasting manner, without the need for additional machine processing in the blind hole and whilst providing other advantages.